Corrosion apparatus



hay 18, 1926.

c.PfToLMAN coRRosIoN APPARATUS Original Filed March 15.1921 2 sheets-sheet 1 'lJ//l By MPM 7%7 May 18 1926. 1,584,906-

' C. P. TOLMAN CORROS I ON APPARATUS original 'Filed March 15,v 1921 2 Sheets-Sheet 2 W JMW A TTORNE YS CHARLES, r. Tonnen. or' una" Your; u. if., sesiones. 'ro nacional', tuen compiuti", os new Y., e. consort-errori oir new ants-snif.

APPARATUS.

.Original application filed arch 15,

this application is ac iris o cation it' r iniprovesents in paratus and manufacture t p Yrial No. fil-5250i, led March l5, 1921, thc

present applicatixonV l L directed to the apparatus, the parent application having been restricted to the process.

Y The invention relates specifically to the manufacture ot White. leadV by the so-calle-d 19 dry pr cess and consists in the provision of ineans whereby the corrosive action orp certain reagents upon inet-allie lead, or the inaterial' to be treated orcorroded, niay be facilitated and the quality ot the product controlled and irnproved and whereby `varier-.s

coincident advantages are obtained `indrespec-t to oost of manufacture and sanitation as hereina'lter made apparent.V ln its pre'- Jef-red forni, the invention comprises an ap- 29 paratus for conducting the corrosive treatnient continuously and by the aid of mechanism adapted to niaintain uniforin reaction, and also comprises features hereinafter described. Whichare capable of use in other relations'than in the manufacture of White lead and which are herein independently and broadly claiined on that ac'count.V y

For many years lp'ainters White lead has been manufactured by the `so-called dry d process according towhic'h abatch of pulveriZed inetallic'lead is tunililed in a closed .roi- Vtary cylinder in the presence o''corroding rea-rents consisting of carbon dioxrd, air, Water and acetic acid. rl`he lead is pulrerized by steanihlast atoinization Whenin a inolton state. and is charged into the cylinder through a' door at the topfwlien the cyl- 'nder is at rest, being a the saine tune sprinkled with an' aqueous 'solution of the acid. rlhe cylinder is then closed and set in rotation and a. flow of the gaseous reagents is passed through it in the meantime.l rlhese gaseous reagents are purified furnace gases containing C02 and air. vllroni tune to time the cylinder is opened by an operative who sprinkles lor Wets down the interior With liquid reagent by the use or a hose, and at the end oit' sonic six or seven days the original metallic lead particles becoine thickly 5l; coated with, or more or less completely con-l verted into, the White basic-carbonate o'l lead, connnercially knownA as White lead'. Because of the presence Vof lunops and uncorroded lead particles, the product of this first stage of the process, is next ground or n ot ny applicoi'i'osion apsemi No. sere-e5.

o White lead, Se-- .lcd and this application filed .Taililary threshed so as to break up the lumps and expose the metal by removing the crust troni the inconipletely corroded particles. It is then subjected to a repetition or the' ysaine corrosive trea'tnienJr in another cylindervfoi a siinilar Qeriod or until substantially all ot' the metallic lead has been corroded, Whereuponthe contents of the cylinder are tra-shed to separate thein troni any still remaining metallic particles or particles of coarse car'- bonate. Soda is added to the Wash water to neutralize acid, and the niass is dried and jfiaclred, or ground in oil and packed as desired.

The cheniic'al react-ions con'stituti'ng` corrosion are complex and need not be described. They are recognized to be sucesssiye or cyclic in character on which account it has been assumed to be desirable to int-roduce the liquid reagents, by sprinkling', only at certain vspecified intervalsA on the theory that conditions of alternate Wet-ness and dryness are necessary, or at least desirable, in order to promote the desired action and produce the best results. It is the general practice to sprinkle the corroding inass tiyic'e every twenty-four hours, both sprinltlings ccuring within one of the eight hour shifts of the day, the contents of the cylinder being allowed to dry out during the followingsixzteen or "-icre hours of each day. rlie 'eilf'ort to inoisten thoroughly the entire dried out inass on the next succeeding sprinkling al- `ays results in such a general condition oit 'wetness and local pastiness, to cause the partly corroded powderous lead to ball up into lumps and also to calre and stick on the cylinder Walls so that it is necessary to pound the Walls attrequent intervals with heavy nauls, operated by nia-n or power to dislodge and break it up, and suoli pounding is a necessary part of the corrosion proc'- ess as now practiced, because the agglomerat-ion of the inass iinp-risons and shields inuch ott the metallic .lead from. contact with the corroding` reagents, and thus not only stops or slows down the reaction but also increases the aniount of lead Wasted as tailings. The pounding, though necessary, is also objectionable in that it rapidly Wears out the cylinders, besides Which it dislodges into the rooin a. great deal of dust consisting largely of lead which is poisonous to breathe, and inaltes it imperative that the Workers' be carefully protected,

C ti

According'to my novel process, which the apparatus I have invented may be used to carry out the corrosive reaction is accomplished and controlled by the introduction ot the liquid reagent into the corroding chamber, whether oit the rotary type referred to or ot any other form, with the view o't keeping the mass always moist, though not to an extent to make it pasty and without allowing it to become dried out for any considerable length of time until it is ready for discharge or until the corrosion is completed. By closely controlling the amount of liquid reagent, water or water and acid, introduced, and distributingr it thoroughly throughout the mass and preterably so to keep a certain percentage constantly present therein, l have succeeded in producing the desired corrosion in a shorter period, with the use ot less acid and also with marked diminution oit the tendency to ball up into lumps or adhere to the chamber walls and without the neer. tor the customary pounding. For this purpose the liquid does not require to be continuously introduced but may be supplied at intervals, provided the intervals are sui'iiciently regular and provi-ded the mount supplied is appropriately gaugcd to maintain a substantially uninterrupted semi-dry and nonpasty condition. The suitable percentage ot moisture may, and should vary according to conditions and requirements as later explained but should not run less than two per cent nor more than tive per cent, by weight referred to the moist corroding` mass as the percentage base. For example, by increasing the number ot sprinklings from two per day (both occurring in one ot the eight heur shifts as above mentioned), to six sprinklings per day occurring at substantially equal intervals ot tour hours there results an improvement in total production ot upward ot titty per cent, represented by a reduction of the corrosion period by approximately two days, the use ot less reagents and the attainment ot a superior product with less tailings. More 'frequentsprinklings under the same conditions give corresponding further improvement, and especially when the amount ot liquid used, is properly coordinated to the progress ot the corrosion.. that is to say, it is desirable to introduce the liquid reagent', rather treely during the initial es tapering it oir as the corrosion progr nees, using no acid during the final sta-ges or no more than will sufiice to maintain the requisite temperature tor the reaction, but always adjusting the 1rater supply so that the necessary moisture condition will obtain as above explained.

The foregoing process may also be performed continuously, by causing the lead to advance as a continuous or substantially continuous stream from a place ot teed to a place of discharge and in the presence of the reagents which produce the corrosion. By such arrangement the succesire regions or sections ot the advancing stream will rorrespond to successive stages in the progress ot the corrosion, sequence in time being thus converted to sequence in position, which atlords the advantage that each stage can be treated with the liquid reagent according to its individual requiren'ients and by means of automatic machinery which can be set to work with practical intallibility so as to maintain a uniform character ot reaction at every stage and a standard output for the process both as to quantity and quality.

The accompanying drawings represent the preferred form of apparatus Alor continuously carrying out the process as just referred to and tor other uses ot which it is capable.

Fig. l represents in side elevation, a rotary corroding chamber broken away at the center and partly in'section.

Fig. 2, a typical cross section ot that chamber on larger scale.

Fig. 3, a. longitudinal section through the feed end.

Fig. 4, an end elevation of the feed end, parts being in section.

Fig. 5 is a detail section ot the automatic sprinkler shown in Fig. Q, and

Fig. 6 is a diagram of the moisture supply system.

rEhe corro-ding chamber consists ot a long, substantially horizontal and preterably cylindrical tube l, constructed ot wooden planks or staves mortised together and bound with circular bands 2, serving tracks by which the chamberrer s upon the rollers 3, which latter are iirmly journalled on a foundation and provided with tianges appropriately engaging the tracks to prevent endwise displacement ot the chanioer. At intervals along its length, the chamber is provided with annular gear racks t mesh* ing with pinions 5 driven by the longitudinal power shatt (i, which rotates the chainber on the rollers. Power is applied to the drive shaft preferably at the middle so that the strain ot driving is equally distributed and the drive is preferably continuous in one direction although. it iiiigfjht be oscillatory. The chamber shown in the drawing may be assumed to he soule 9.1 tert long and (i Vteet outside diameter, although there is no limitation in this respect, and the annular tracks may be about si.. 'feet apart. r"'he chamber is interiorly lined with heavy paper T (Fig. 5) and covered with a layer ot matched boards Fi, lil-:e ordinary flooring, thus producing a composite or laminate wall structure ot c-:cellent heat retaining qualities and hence the least conducive to the condensation ot' moisture on the interior which would tend to cause the CLI material therein to stick to the innerc surface. vi

The ends of the chamber are closed by bulkheaos each properly accommodated to the feed and discharge mechanisms. The

bulkheads 9 at the feed end is provided with Vthe gaseous products of combustion received from the scrubber and which constitute the supply of carbon dioxide and air.` Metallic lead pulverized in the usual Way 1s introduced into the chamber by the central feed spout 12, which is also formed in said structure betveen the gas spouts 1l. ln this Vposition the gas entrances are in non-dripping relation to thefeed spout so that 'any moisture condensing from the freshly scrubbed gas and dripping from` such entrances 7vvill not Wet any part of the lead spout which would cause it to accumulate a coating and eventually an obstructing mass of lead. The pulv riZed or granular lead, or the material which is to be converted into White lead, is supplied to the spout 12 from an automatic feed mechanism (Fig. l), of any suitable design but which is encased` or enclosed Within a. housing. lt comprises in the present ease a supply hopper 13 opening onto the central part of the upper stretch of a Wide fiat belt 1d, and provided with a lateral opening and van adjustable gate 15 t ierefor to control the rate of delivery to the belt. This gate is adjusted by the recit and pinion 16 manually operated by the Worm shaft 17.

The feed belt 1d is enclosed in` the upper part of a feed hopper 18 leading to the feed spout 12 and iis appropriately mounted on pulleys therein and arranged to be driven in the direction indicated so that `lit will WithdranT lead from the hopper gate and discharge it into the lead spout. rlhe rate of such discharge is `obviously controlled by the rotation of the belt pulleys, and such rotation is accomplished, in the case in hand, automatically and preferably by a connection to the rotating chamber. For this purpose one of the pulley shafts is extended through the enclosing casing and d 'iven/by a sprocket and chain 1.9 and a star Wheel 20, the arms of which are located in position to be engaged by pins 21 projecting from the feed end bulkhead 9. By controlling the gate l5v or the number of pins 21, or both, the rate of feed of metallic lead to the chamber can be regulated as desired and can be set to conform closely to the progress of the process.

The lead thus introduced is advanced through the chamber gravitationally and by the effect of the rotation of the latter, and a suitable rate of advance is secured if the anis of rotation is exa ctly horizontal and the chamber maires say, sin revolutions per hour. Under the normal practice this will cause the passage through the chamber to be made in about tive days, and the lead Will in the meantime be subject to continual agitation or lateral change of position as it tumbles or rolls around the interior, so' that fresh surfaces of the mass are constantly presented to the action of the reagents. sary to equip the interior of the chamber with lift-ers or venes for promoting the travel of the lead, although these may be provided if desired. An adequate range of adjustment of the rate of advance can be secured by proper co-relation of the rates of lead feed and chamber rotation.

The bulkhead at the discharge end is provided With a short extension 23 of reduced dia noter, closesly fitted to and revolving Within a stationary bonnet 2d which is connected to the suction side of a blower or exhaustsystem diagr inmatically indicated atr 25, the purpose of which is to cause the gaseous reagents to flow from spout 11 through the chamber a. negativepressure, slightly less than atmosphere, Within the chamber and Within the housing of the lead-feeding apparatus. The discharge end of the chamber is also equipped vWith a. flight of curved vanes 26 for lifting the treated lead into said reduced section 23, from which it is discharged into a suitable chamber, as for example, into the trough of the screw conveyor 2'?, Which is disposed in the lower part of the enclosure 24 directly beneath 'the end of said reduced discharge `xtension 23. As a precaution against the passage of lumps into the con veyor, which might obstruct it, the section 23 is formed with a latticed or reticulate margin as indicated at 29, the openings of which are predetermined With respect to the size of the conveyor. The lattice formation serves also to break up such lumps as happen to be deposited upon it, by the rolling effect. A door Q8, provided 1n the bonnet structure, affords means of access to th chambers and closes to a position adjacent said latticed margin as indicated. lt will be understood, that the treated lead may be discharged either by continuous of intermittent delivery.

The novel features of the rotary corroding chamber above described may be usefully employed with any kind of means, for introducing the liquid reagent, or reagents, used for corroding the lead, Whether manual or automatic. The system herein shown is automatic and Vaffords special advantages in respect. to the type of chamber described although it is also capable of use-in the nonlt is not neces.

and also to maintain Y continuous process, and in other relations as vill presentlj.v appear. rlie said system involves the use of one or moie liquid conductinfr pipes or passages, such as 30, pernianentlj,Y niounted in or on the elianiber call and serving` to conduct the liquid reargeut from an outside source and distribute it. as a spra'v. over the mass of lead within the ch: ailier. Vl`lie pipe terminates in a spray nozzle 3l which is so located, when in action, as to direct its spray into uni- 'l'o nilv distributed contactwitli the lead bel it and so that piacticall)Y none ot the liquid stril-es the chamber wall, this being due to the shape and angle ot' the fine spia'v slit oi the ozzle orifice as 'Cell as to the location of nozzle with reference to the lead when the liquid is passed through it. The lf-ad norinalljvv assu nes and naintains (he p ftion indicated in Fig'. Q, the rotation being in the direction ol the arrow, and it is to he noted that the Xtent of inward projection et the nozzle eziceeos the normal depth et the hed ot ead so that its sprayY oriiice projec s above the saine. and does not there- 'tore lecome clogged with lead particles. when he nozz e pipe is carried through the lower part ot its path and the lead tumbles over or around it. The spray nozzle and also such other parts ot the moisture supply sysare exposed to the interior of the chan'ilier, are so arrangedy or otherwise constituted. as to prevent rapid escape of heat through them to the exterior (the corrosion reaction l eine, erv'otherinic) so that their siii'- lace temperature is thus caused to approximate that ot' the gases in the chamber, or at. least, is kept above their dew point. This n ay be accomplished by inaltinc; said parts ot a material ot poor heat coin ictinp; quality7 or bv appropriately heat-insulating them when they are made ot metal, and the latter method is employed herein. Such heat protection insures againsty the condensation of moisture on said parts and thereb v prevents the accumulation ot heavy,v masses ot corroded lead upon them. ln the present case the nozzle pipes 30 are double-walled or jaclqeted with a surrounding; pipe 8:2 l'orniing;- an interveningair space wl ica suinicient to u ale them non-condensing. The space between the pipes also arciiininodates a haiuiiier ll. in the 'torni of an annulus enibacingi' the innei' pipo and ad: l@ted to slide thereon. When the nozzle pipe attains a siilticientlv dependent position this lianiiner slides down it, and by its iinpact e.g i'aiiist` the nozzle head jars loose anir material which maj: have adhered to it, thus keeping' it clean. )i rounded or bevelended collar S-l on the pipe 30 serves to detain the hammer in its outermost position a; the pipe approaches verticalljv7 so that the hammer does not slip otl" the collar until the pipe is nearly vertical, thus insuringthe clem teni as position to be carried thereby into a tant: oi liquid 3G located directly,v beneath the chainbei. 'l he receptacle nrovrled with a lillinghole 3T by which it is charged with the liquid during' immersion. as it passo: through the tanl;1 and with an adiustabh overflow tul vhich presfa'ibei:` the. amount ot li(` uid renianinal in the iei-e tiii-le as it leaves the tank. The outlet from this diiriper-receptacle is controlled by a dif-c valve Ill operated b v a weighted lever 39, so that the outlet remains closed during the process ot filling and is not opened until the otation ot the corroding chamber has carried the c xnter o gravit),v ot the leve over its t'ulcruni support. rl`his does not occur until the nozzle 3l assumes substantially the angle indicated in Fie'. Q in which it is in the correct position above referred to and wherein the elevation oi tlie dipper abore the nozzle provides a suimcient hvdrostatic head to produce vigorous spra}.'iiig and spread the liquid out in a 'trie-shaped ,spray ore a considerable area o'l' the lead mass. but not upon the chamber wall. The liquid reservoirs are connected by pipingl0 vith a inain water supply tank lil (Fig. 3).

li l as b v means wi-,erein the level is contr lleo.. ot e tient-valve lll or otherwise at the level desired for the seve al reservoirs. also connected by piping- -ll with a similar float-controlled supplyv tank l5 containing' an acid reagent and appropriate valre connections 42 aie provided so that the liquid in each reservoir niav contain either water or acid solution, or be eut out ot action, as desired. rl`he tanl-t l5 ot acid reagent will be understood to he supplied from another source -l-'i in which appropriate proportions ol water and acid are measured :zuil niirwd the :ziiore iiefiriibeil i ploved for the continu( us they7 will oi erate on successive zones t the advancing' lead stream and ina uch as their deliver but a small amount or liquid on each on the constantljvv rotation and deposit it changing` urtare, oi'i the lead mass. nie elieetis to produce a homogeneous admixture of the liquid with the lead7 which well adapt- Ythough not necessarily continuous, as above explained, but it is obvious that the nume ber of stages may be more than two it desired according to the Werl: in hand and the character ot the apparatus available. in the iirst stage the treatment is carried on for as long as eiiective reaction is obtained, .that

is to say, until the still remaining metallic lead particles become so imprisoned by theiil White lead coatings as to be shielded from eiiicient c iemical contact with the reagent, and this will be tound to occur in about .five days in the operations as described. he conveyor 2i' conducts the treated material discharged from the iirst chamber to .the threshing or pulverizing apparatus wherein the metallic particles are freed from their coatings and made accessibley for further contaft 1with the corroding reagents. From this operation th,partially'corroded mass is conveyed and :ted into a second corroding chamber which may be exactly like the first, and the transit through this second chamber results in the corrosion of substantially all et the remaining metallic lead, the resulting product being then ready for Washing, in order to neutralize the Aremaining acid, and the other usual finishing steps. For the chamber Working on the irst stage the several clippers and their liquid supply means are set so that'in the first three or four spray zones the lead is liberally supplied withA acidy solution; the remaining vnozzles are set to spray With Water only, or

with a Wea-ker acid solution according to the amount supplied in the earlier zones eacept as to the last two or three Zones, which may be cut ed' entirely or used tor either Water or acid as the moisture conditions require. In this Way the rate ot supply of acid to tliemass is diminished as the corrosion progresses. For the second corrosion also, the acid is similarly regulated, the first zone only receiving acid solution and the rest only Water, excepting those which are cut out as the moisture conditions happen to require, and it is generally desirable to allow the mass to dry out as it approaches the termination of the tirst corrosion. ln both stages, the amount ot acid required to be introduced with the Water is less than heretofore and the solutions used are also weaker-114% being generally sutiicient Where 6% has been heretofore considered standard.

'ifo satisfy certain existing commercial demands it is desirable that White lead shall coni-ain a certain portion et White lead particles ot relatively larger size than the rest, when viewed microscopically, or rather, that it be constituted ot' an assortment of partic-les ot ditiercnt size ranging from miniiineness up to a predetermined maxian excess of large particles being, ver, objectionable in that it makes the product sandy. rlfhe exact causes ot thc ilevelopmeut oit coarser particles have not heretofore been understood, but I have ascertained that their production depends upon, and can Vbe controlled by, the moisture condition during corrosion. That is to say, it' the process be run relatively dry the eiiect is to make larger particles and it run meister, to malte liner particles and I set the adjustn'ient oi' the spray system accordingly, bearing in mind Vthat the moisture conditionA is generally somewhat higher in the immediate proximity of the spray points than between them, and l allow i'or this variation or malte use or" it, tor the purpose stated, that is to say, by adjusting the system so that the adY-.f'ancing stream will, tor a suitable time in the aggregate, contain that greater percentage et moisture which yields the finest size particles and tor the rest of the time Will contain less moisture suited to yield the coarser particles. lit is not a diiiicult matter to ascertain the relative pro# portion or degree ot coarscness in the corroded product and with this intorination in hand it is easily possible to vary the number ot spray nozzles in action or the ami-cunt ot their deliveries, so that the aggregate time of relatively moist corrosion shall bear the proper relation to the aggregate time ot kthe less moist corrosion and thereby aroduce the exact quality of White lead that may be required tor a given purpose. My invention thus consists in the control ot the duration ot the relatively more moist and the relatively less moist corrosion periods to the end of controlling the proportional amount ot the coarser patricles and also the size thereof, and by such means l am enabled to obtain the desired finished product With the least loss in the torm| ot tailings. Sampling holes are provided at frequent intervals along the chamber, though not shown in the drawings, and,` by means of these the moisture condition Within may be ascertained from time to time, but it will be apparent that once the moisture system has been properly set it is not likely to require change except as the result ot a change in the rate of flow or the relative hui'nidity ot the gas flow. YVith gas taken direct trom the scruhbers the relative humidity is substantially constant and with appropriate regulation the lovv variation may also be lll dill ykept Within reasonable limits.

l claim the following:

l. Lead corroding` apparatus, comprising, a rotary chamber, axially-disposed means for introducing a gaseous reagent into the chamber and non-aXially-disposed means for soY Cil

introducing a liquid reagent thereinto While the chamber is rotating.

Lead corroding1 apparatus con'iprisinze,` a rotary corroding chamber in combination with means having' a close-iittingjoint with said chamber for supplying' a gaseous reagent thereto While maintaining therein a negative pressure and means ior introducing a liquid reagent into the chamber While rotating. n

3. Lead corrodingr apparatus, comprising; a rotary corrodinp; chamber in which the lead is agit-ated in a semi-dry, non-pasty condition, and a liquid spraying; means located in a position in the chamber wherein it sprays the lead Without wetting the chamber Wall.

Lead corroding apparatus comprising, a corroding chamber formed of heat insulating,r material and metallic means extending trom the exterior to the interior ot said chamber ior the delivery thereto ot a material igor reaction or treatment therein, said metallic means being` constituted to maintain a. non-moisture-condensing temperature, so as not to accumulate masses ot material thereon.

5. Lead corroding apparatus comprising a corroding chamber in which the lead is agritated during corrosion, a moisture supply system including# nozzles Within the chamber, the parts of said sstem exposed to the interior of the chamber' being adapted to assume and maintain a surface temperature above the dew point oin the gaseous contents of the chamber.

6. Corroding apparatus comprising, a rotary corroding chamber in which the material to be corroded or treated is tumbled during` corrosion, and a moisture supply system comprising one or more nozzle members projectinginwardly from the chamber wall and of `greater inward projection than the depth et the tumblingmass.

7. Lead corrodincY apparatus comprising a rotary corrodingr chamber, in which the lead is tumbled during corrosion. the Wall thereof being made ot low heat conductivity and a moisture supply system having one or more nozzles projecting into the chamber. interceptine,` the tumbling mass. and prot-.vided with heat-insulatinf,r protection adapted to prevent condensation thereon and consequent accumulation of lead masses.

8. Apparatus for introducing liquid into rotary chambers comprising, a liquid conducting' pipe or passage located on and e5;- tendmgr through the Vall ot the chamber7 in combination with means Jfor deliveringY liquid through said passage at a predetermined point in the path thereot1 and spraying it into the chamber.

9. Apparatus ttor introducing liquid into rotary chambers comprising7 a liquid conductingV passage located on and extendingthrough the ivall ot the chamber and carried thereby i'rom a lou' to a higher position in combination ivith means for delivering liquid. through said passage and a gravitycontrolled valve tor said passage.

l0. Apparatus for introducing liquid into rotary chambers comprising'7 in combination, a receptacle carried by the chamber. a relatively stationary source ot' liquid supply from which the. receptacle is charged and an outlet from the receptacle extendingr into the interior ot' the chamber and through which the liquid is delivered Within the chamber.

ll. Apparatus for introducing liquid into rotary chambers to material agitated by tumbling therein comprising a liquid conducting pipe or passage located on and ef:- tending through the ivall o't the chamber and having its outlet above the tumbling mass, in combination with means ttor delivering liquid through si id passage at a predetermined point in the path thereof.

l2. Apparatus t'or introducing liquid into rotary chambers comprising a liquid reservoir mounted beneath the chamber, a. dipper mounted on the chamber and arranged to charge itseli by immersion in said reservoir and sprayer means associated ivith the dipper :tor delivering liquid therefrom to the chamber.

13. Apparatus for introducing liquid into rotary chambers to material agitated by tumbling therein comprising aJ receptacle carried by the chamber, means ivhereby the receptacle is charged ivith liquid and a vali-'e-controlled passage between said receptacle and chamber having` its outlet Within the chamber aboi'e the tumbling mass.

llt. Apparatus for introducing liquid into rotary chambers comprisinga liquid-containing receptacle carried by the chamber, a valve-controlled outlet trom the receptacle to the chamber and means for opening the valve at a predetermined point in the path ot the receptacle adjacent the upper part ot the drum.

l5. Apparatus for introducing liquid into rotary chambers to material agitated by tumbling therein comprising a liquid-containing receptacle carried by the chamber, a liquid conducting pipe or passage located on and extending' through the ivall ot the chamber and having its outlet above the tumbling mass, iu combination 'with a valve controlling` the introduction ot liquid and means .tor opening the same at a predetermined point in the path o1"- the receptacle.

1G. Apparatus for introducingr liquid into rotary chambers comprising, a liquid receptacle on the chamber having' a discharge to the interior thereof. means for charging the receptacle with liquid and means for limiting the amount et the charge.

17. Apparatus tor introducing liquid into rotary chambers comprising a dipper mountieu iii-,seance ed to travel about the chamber axis and adapted to charge itself from a liquid reservoir mounted bel-ow the chamber and an adjustable overflow forthe dipper.

18. Apparatus for spraying liquid in horizontal rotary chambers comprising a dipper mounted on the peripheral chamber Wall and provided with a radial outlet pipe terminating in a spray nozzle in the chamber, a reservoir from which the ydipper is charged while in a lovv position, a. valve controlling the flow to the spray nozzle and means for opening said valve When the chamber has carried the dipper to higher position.

l. Lead corroding apparatus comprising a substantially horizontal rotary corroding chamber containing granular metallic lead, i receptacle .mounted on the peripheral Wall, means for filling the receptacle With a liquid reagent while occupying a low position, a spray nozzle Within the chamber connected to the receptacle, a valve for the connection and means for opening the valve When the receptacle has been carried to higher position.

20. ln lead corroding apparatus, a rotary c'orrodino' chamber, a spray nozzle mounted in inwardly projecting relation on the Wall thereof and automatic means for dislodging ter adhering to the nozzle.

2l. ln lead corroding apparatus, a corroding chamber provided With a spray noz- Zle Within the chamber and a hammer 'coacting with the nozzle to clear it of adhering matter.

ln lead corroding apparatus, a. rotary corroding chamber and a double-Walled spray nozzle mounted therein and projecting toward the center of the chamber.

23. ln lead corroding apparatus, a rotary corroding chamber having a laminated Wall structure With an interior layer of heatinsulating material.

24. ln lead corroding apparatus, a rotary corroding chamber and a moisture supply system correlated therewith to supply moisture there-to by the effect,vand in proportion to tie rate, of rotation of said chamber.

25. Lead corroding apparatus comprising, a rotary chamber having` a feed entrance for metallic lead at one end, a discharge outlet for treated lead at the other, means for passing a gaseous reagent through the chamber, and means for introducing a liquid reagent into the chamber at a rate proportional to the rotation thereof.

Q5. Lead corroding apparatus comprising, a rotary corroding chamber in Which granular lead is subjected to gravitational advancement by the effect of the rotation, a feed entrance at one end of said chamber through which metallic lead may be introduced duringthe rotation, a discharge opening at the other end through Which the corroded lead may be delivered during the rotation, and means connected with said 'chamber for asslnO a 'aseous rea ent at a neo"- l b zu :a ative pressure through the same during theI rotation thereof.

2'?. Lead corrodmg apparatus com sing i l N l.'. a rotary cnambr-r having clase-nt-v b feed and exit entrances througl'i which granular metallic lead may be introduced and treated lead discharged during the rotation tl' reef,

means for maintaining a negative pressure horizontal stream, means for maintaining a gaseous reagent within the chamber, spray nozzles mounted at point-s distributed along th'elength of said chamber and stream and means for supplying liquid reagent to such nozzles. v

SO. Lead corroding apparatus comprising, a corroding chamber through which the lead is advanced during corrosion, 'and an automatic moisture supply system for supplying -liquid reagent thereto comprising `a .succession of spray-nozzles and means for maintaining a uniform hydrostatic head on each nozzle.

3l. Apparatus of the kind described comprising a rotary chamber in Which the material to be treated is advanced by the effect of the rotation and spray means within the chamber automatically controlled by the rotation of said chamber.

32. Apparatus of the kind described comprising a rotary chamber in Which pulverized material is advanced by the effect of the rotation, a series of liquid receptacles mounted on said chamber Wall, a series of .spray nozzles therefor located Within the chamber and means for charging the receptacles with liquid.

33. Apparatus of the kind described comprising a rotary chamber through which material is advanced by the effect of the rotation, a reduced extension on the discharge end thereof, an enclosure closely litted to said extension, a conveyor in the enclosure and means for maintaining a negative pressure in the chamber and enclosure.

34e. Apparatus of the kind described comprising a rotary chamber through which material is advanced by the edect of the rotation, a reduced extension on said chamber, a reticulate end portion therefor CID adapted to prevent discharge ot lumps there'trom and a conveyor receiving' the material passing through the retieulations.

H5. In lead corrodinfr apparatus, a corroding` chamber through which pulverized lead is advanced in a semi-dry condition, a feed spout constituting an entrance tor the lead and means for admitting a gaseous medium inte the chamber adjacent to said 'leed spout but in non-dripping` relation thereto.

36. In lead corroding apparatus7 a closed, rotary corroding` chamber, a stationary structure eoneentrically fitted to the end bulkhead thereof containing a downwardly and forwardlyY extending feed passage for lead and a feed passage for gas.

37. In lead corroding apparatus, a rotary eorroding chamber, means for maintaining a negative pressure therein, a lead feed spout leading thereto, means for measuringand delivering lead into .said feed spout and an enclosure i'or said 'feed means subject to the negative pressure in said chamber.

38. In lead corrodingapparatus, a closed rotar7 corroding chamber. a feed entrance7 av hopper opening ont-o a traveling surface for depositing' lead in said feed entrance. an enclosure for the end of the hopper and said surface and means for maintaining a negative pressure in said chamber and enclosure.

39. In lead correding apparatus. a rotarv chamber, means for feeding pulverized lead thereinto comprising a hopper opening onto a traveling surface and means vfherehy the retain;v ehamher drives said surface.

`it). In lead corroding apparatus a rotary corroding chamber. dipper and deliver-ine means i'or supplying the chamher with liquid, a series ot reservoirs enacting with said means and a. commom constant-kwel supply tank for supplying said. reservoirsI connected therewith to maintain an equal liquid level in all ol" them.

4l. In lead correcting,` apparatus. a rotary corroding chamber, dipper and delivering means for supplying .liquid thereto. a series of reservoirs eoaeting with said means, and two constant-level supplyv tanlis connected to each of said series of reservoirs and arranged to establish the same liquid level in all of them.

42. In lead cori-odina apparatus, a rotaiav eorroding chamber, a series of reservoirs heneath the same and liquid spraying means mounted on the chamber adapted to he supplied. respectively7 from said reservoirs. in combination with means for optionall)y admitting; n'ater or acid to said reservoirs.

43. In lead corroding apparatus a rotary eorroding chamber7 a series et sprajvv devices carried therehy, a common source ol" liquid ior said devices. and means nhereliv said devices may he individually eut out ot action.

In testimoniv whereof, I have .signed this speeitication. i

CHARLES l). TOLMAN. 

